Reservoir and tank arrangement for hydraulic presses



Nov. 27, 195] w, ERNST I 2,576,584

RESERVOIR AND TANK ARRANGEMENT FOR HYDRAULIC PRESSES Original Filed Sept. 15, 1949 3 Sheets-Sheet l INVENTOR WALTER ERNST 7914M mgml fl ATTORNEYS Nov. 27,1951

w. ERNST RESERVOIR AND TANK ARRANGEMENT FOR HYDRAULIC PRESSES 5 Sheets-Sheet 2 Original Filed Sept. 15, 184;

INVENTOR WALTER ERNST BY 351mm M ATTORNEYS Nov. 27, 1951 ERNST 2,576,584

RESERVOIR AND TANK ARRANGEMENT FOR HYDRAULIC PRESSES Original Filed Sept. 15, 1949 3 Sheeis-Sheet 5 66 L2 u I04 r /uo IOO u I08 J 5/7313 I06 f\ I i I INVENTOR WALTER ERNST ATTORNEY Patented Nov. 27, 1951 RESERVOIR AND TANK ARRANGEMENT FOR HYDRAULIC PRESSES Walter Ernst, Dayton, Ohio, assignor to The Commonwealth Engineering Company of Ohio, Dayton, Ohio, a corporation of Ohio Original application September 15, 1949, Serial No. 115,901. Divided and this application December 1, 1950, Serial No. 198,670

11 Claims.

This invention relates to hydraulic presses, and in particular to a reservoir and tank arrangement by means of which certain beneficial results are obtained. This application is a division of my copending application Serial No. 115,901, filed September 15, 1949.

In the construction of modern hydraulic presses it is customary to provide a power unit integral with the press and preferably mounted on the head thereof in order to locate it in a convenient position and to save floor space. A power unit of this nature will comprise a fluid reservoir, a pump and a drive motor for the pump with the pump being connected to the driven part of the press. Presses of this type are widely utilized for a variety of work operations, and in most cases it is desired for the press to operate as rapidly as possible in order to produce as much work as possible.

Due to the fact that the presses do operate at high speed, the oil movement from the fluid reservoir is also quite rapid, and this sometimes leads to there being voids in the oil supply. This phenomenon is known as cavitation and is highly undesirable, because it not only slows down the press, but makes the operation of the pump inefiicient and induces noise and vibration in the press.

The fluid medium employed in a hydraulic press of the nature referred to, and which is usually oil, must be cleaned at intervals in order to prevent foreign matter from accumulating in the oil and affecting the operation of the press or pump or causing wear or abrasion of the finely finished .parts of the pump and press. This is ordinarily done by periodically removing all the oil from the press and cleaning it by normal oil cleaning actions, such as by centrifuging or filtering, but an operation of this type is not readily carried out on the usual type press. In other cases, a filter unit is embodied in the hydraulic circuit of the press, and this in general is satisfactory but involves a great deal of expense.

The primary object of the present invention is to provide an arrangement for the power unit of a hydraulic press which overcomes the disadvantages referred to above.

A particular object of this invention is to .provide a fluid reservoir and tank arrangement for the power unit of a hydraulic press such that the press may be operated at high speeds without there being any danger of cavitation of the oil supply to the pump.

Another particular object is the provision of a 2 reservoir and tank arrangement for a press such that the system can readily be cleaned at any time without the need of an expensive filtering unit or without removing all of the oil from the press These and other objects and advantages will' become more apparent upon reference to the following description taken in connection with the accompanying drawings, in which:

Figure 1 is an elevational view of the upper or head end of a press embodying the elements of my invention;

Figure 2 is a side view of the head end of the press looking in at the right side of Figure 1 showing the reservoir and tank arrangement;

Figure 3 is a vertical section through the head of the press and is indicated substantially by usual head and bed interconnected by spaced uprights and joined together by strain rods or any other suitable load carrying means.

In Figures 1 and 2 the head of the press is indicated at I!) and the uprights which support it on the press bed at [2. A platen I4 is reciprocably mounted between the head and bed and may be guided on the uprights and is adapted for being driven by a ram It.

Turning to Figure 3, the ram it will be seen to be double acting and extends into a cylinder l8 mounted in a bore 28 in the press head. The lower end of cylinder is is flanged, as at 22, and there are bolts 24 by means of which the flange is bolted to the lower side of the press head. It will be evident that any downward thrust on ram IE will be transmitted to cylinder [8 and act upwardly through flange 22 on the bottom of the press head.

Ram it may have a bore 26 into which extends booster ram 28 that is secured to the closed upper end of cylinder [3. Fluid is adapted fo being supplied to the upper end of cylinder l8 by a com duit 3t and fluid is supplied to the bottom of cylinder 58 by a conduit 32. The conduits 3%] and 32 are permanently affixed in the press head 7 when the press is manufactured, and a simple fitting 36 serves toprovide a detachable connection between conduit 30 and the upper end of I 3 cylinder l 8, while a passage means 36 in flange 22 forms the connection between conduit 32 and the lower end of cylinder 18.

The press head I hasmounted on the upper end thereof a fluid reservoir comprising the upstanding peripheral wall part 38 having a cover plate 40. This reservoir surrounds the upper end of cylinder l8 and provides a supply of fluid to the surge valves 42 in the upper end of cylinder l8 and also receives fluid therefrom. In order to prevent leakage of fluid from the reservoir into the space between detachable cylinder [8 and bore 20 of press head Hi, there is preferably the packing means 4-3 between the cylinder and head that is compressed by the gland 46.

Referring now to Figures 3 and 4, it will .be observed that there is mounted on the'back of the press head a tank 48 which has a partition 50 therein dividing it into a first compartment 52 that supplies fluid to the pump of the power unit, and a second compartment-54. A connection toward the bottom of partition 59 connects compartments 52 and 54, and this connectionis provided with a valve t that may be closed or opened by rotating valve stem 58 by means of knob 60.

Compartment '52 is connected with the reser voir on the press head by conduit 62 that includes a valve 64 in the said reservoir. This valve is adapted for being opened and closed by rotation of its stem 65 by the hand wheel 68. Compartment 52 is adapted for standing under a predetermined head depending on the level of oil in the reservoir, and has its upper end closed in order to withstand this pressure by a gasket means 10, which may directly support the pump 12 mounted on top of tank 48.

Compartment 52 also has a relatively large opening 74 in its lower wall, and this is closed by a cover plate 16 and a gasket 18. The described arrangement is such that a pressure may be maintained in compartment 52, thereby to supercharge pump 72 and to prevent cavitation of the fluid that is drawn from the compartment by the suction line 30 leading to the pump.

The compartment 54 has a pump 82 connected thereto-which is adapted for discharging through conduit 84 into the reservoir of the press. A motor 86 may be provided in association with pump '82 for operation of the pump either continuously or intermittently, whereby the oil may normally be transferred from compartment 54 to the reservoir of the press. In normal operation of the press, compartment 5 stays at no more than atmospheric pressure and because of this may be utilized for accumulating leakage and slippage about the system The usual leakage and slippage lines may be employed for this purpose, but for the purpose of illustration, only the slippage line 88 leading from pump 12 to compartment 55 is illustrated.

The pump 12 is provided with pulley means 90 over which pass belts 92 that also engage pulley means 94 on the output shaft of a motor 95 that is mounted on cover plate 40 of the reservoir on the head of the press. It will be evident that energization of motor 95 will cause pump 12 to be driven. Due to integral controls associated with the pump, but not illustrated in the drawings in detail because they are more or less conventional elements, this delivery of the pump can be varied from a maximum delivery in one direction through zero delivery, to maximum delivery in the opposite direction, and in this manner all movements of and platen are controlled.

The energization circuit for motor 96 is illus trated in Figure 5, wherein it will be seen that a contactor 98 has its energizing coil I00 connected between the power lines LI and L2 in series with a normally open push button station I04 and a normally closed limit switch LSI. The contactor has a first blade I06 that establishes a holding circuit for the energizing solenoid I00 through the normally closed push button station W8. A second blade I09 on the contactor is connected in series between power lines LI and L2 with motor 98 so that closing of the contactor at any time will energize the motor tocause pump 12 to be driven.

In normal operation of the press the valve 56 in compartment 54 will be closed and all the working oil of the press contained in the reservoir and in the pump compartment 52 of tank 48.

The pump 52 will then serve to transfer any slippage fluid delivered to compartment 54 to the said reservoir. However, should it be desired to clean the compartment 52, and in which compartment most of the foreign matter picked up by the oil will accumulate, valve 56 may be opened and valve 54 closed'and pump 82 operated to transfer substantially all of the oil out of compartment 52. Thereafter valve 56 may be closed and then cover plate 16 can be removed and the minimum amount of oil removed from the press so the said compartment can be thoroughly cleaned.

At any time valve 64 is so closed, the switch actuating member Hi] on the stem 66 of the said valve will engage and open switch LS1, thereby preventing energization of motor 96 and thus preventing operation of pump 12. In this manner it is assured that the pump 12 will never be driven when there is an insuflicient supply of oil for it to pump. This is of importance be cause pumps of this nature depend on the fluid that they are pumping for lubrication, and any interruption in the supply of oil to such a pump could cause serious damage within a very short time.

From the foregoing, it will be seen that apower unit fora hydraulic press constructed according the press ram to my invention accomplishes the supercharging of the fluid supply to the suction line of the pump, thereby eliminating cavitation in the oil supply which would cause ineflicient operation of the press and noise and vibration.

The invention also provides a ready means for cleaning the hydraulic system without draining all of the oil therefrom, but at the same time giving access to the tank and reservoir at substantially the lowest point thereof where most of the foreign matter to beremoved from the system would be accumulated.

My invention also provides an interlock to prevent energization of the drive motor any time the main valve communicating the press reservoir with the pump tank is closed.

It will be understood that this invention is susceptible to modification in order to adapt it to difierent usages and conditions, and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. In a hydraulic press having a head; a fluid reservoir mounted on top of said head, a tank mounted on the back of said head "below said reservoir comprising two interconnected compartments, means extending through said head connecting said reservoir with one of said compartments and a pump having its inlet connected with the other compartment and its outlet connected with said reservoir.

2. In a hydraulic press having a head; a reservoir mounted on top of said head, a tank mounted on the back of said head below the reservoir, said tank having two compartments therein, a valved passage means extending through said head connecting said reservoir with one of said compartments, and pumping means having its inlet connected with the other compartment and its outlet conne ted with said reservoir.

3. In a hydrau ic press having a head; a reservoir mounted on top of said head, a tank mounted on the back of said head below the reservoir, said tank having two compartments therein, a valved passage means extending through said head connecting said reservoir with one of said compartments, and pumping means having its inlet connected with the other compartment and its outlet connected with said reservoir, there being a valved connection between the compartments of said tank.

4. In a hydraulic press; a pump for supplying pressure fluid for operating the press, a closed tank to which said pump is hydraulically connected for drawing fluid therefrom, and a reservoir positioned above said tank and also positioned substantially above the said pump, said reservoir being hydraulically connected with the tank whereby the fluid in the tank for supplying said pump is always under a pressure greater than atmospheric.

5. In a hydraulic press having a frame with a head and a pressing cylinder in said head; a pump for supplying pressure fluid to said cylinder, a closed tank to which said pump is hydraulically connected for drawing fluid therefrom, said tank being on one side of said press, a reservoir on top of said press head above the level of said tank and also substantially above said pump, and conduit means connecting said reservoir with said tank whereby the fluid in said tank is maintained under a predetermined head above atmospheric pressure at all times, thereby inhibiting cavitation in the fluid supply to said pump.

6. In a hydraulic press; a press frame comprising a head with a pressing cylinder therein, a reservoir mounted on top of the press head, a

closed tank mounted on one side of the press head below the level of said reservoir and conduit means communicating said tank and reservoir, a pump mounted on said tank and connected to draw fluid therefrom and adapted for supplying pressure fluid to said cylinder, and means for interrupting the communication between said tank and reservoir.

'7. In a hydraulic press having a frame with a head and a pressing cylinder therein; a reservoir mounted on top of said head, a closed tank mounted on one side of said head below said reservoir and comprising a pump compartment in communication with said reservoir, a main pump mounted on said tank connected to draw fluid from said pump compartment, and adapted to supply pressure fluid to said cylinder, said tank having a second compartment for receiving exhaust fluid, and pump means for said second compartment for pumping the fluid therefrom to said reservoir.

8. In a hydraulic press having a frame with, a head and a pressing cylinder therein; a reservoir mounted on top of said, head, a closed tank mounted on one side of said head below said reservoir and comprising a pump compartment in communication with said reservoir, a main pump mounted on said tank connected to draw fluid from said pump compartment, and adapted to supply pressure fluid to said cylinder, said tank having a second compartment for receiving exhaust fluid, and pump means for said second compartment for pumping the fluid therefromto said reservoir, there being a valved connection between said compartments.

9. In a hydraulic press having a head; a reservoir mounted on top of said head, a closed pump tank mounted on said head below said reservoir and communicating therewith, means for interrupting the communication of the tank with the reservoir, and a removable cover plate on the lower part of said tank for permitting cleaning thereof.

10. In a hydraulic press having a head; a reservoir mounted on top of said head, a closed tank mounted on the back of said head, a valved connection from the reservoir to the tank, and a removable cover plate on the bottom of said tank to permit cleaning thereof.

11. In a hydraulic press; a press head, a reservoir mounted on top of said head, a closed tank mounted on the back of said head and having two compartments, a valved connection between said reservoir and one of said compartments, a valved connection between said compartments, pumping means adapted for withdrawing fluid from the other of said compartments and for transferring it to said reservoir, and a removable cover plate sealingly mounted on the lower wall of said one compartment and removable therefrom for cleaning the said one compartment.

WALTER ERNST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,077,894 Patrick Apr. 20, 1937 2,184,665 Ernst Dec. 26, 1939 2,354,034 MacMillin et a1 July 18, 1944 2,423,120 Sedgwick July 1, 1947 2,463,003 Stacy Mar. 1, 1949 

